1. Field of the Invention
The present invention relates to an ultrasonic linear motor using an ultrasonic vibrator, and more particularly, to a vibration wave linear motor that can be reduced in size with a simple configuration.
2. Description of the Related Art
In recent years, attention has been paid to an ultrasonic motor (vibration wave motor) as a new motor replacing an electromagnetic motor. This ultrasonic motor has advantages such that (a) high thrust at a low speed can be obtained without a gear, (b) holding force is high, (c) a stroke is long, and a resolution is high, (d) noise is very low, and (e) magnetic noise is not caused, and noise influence is not exerted in comparison with a conventional electromagnetic motor.
As a conventional ultrasonic motor having such advantages, a linear-type ultrasonic motor as one basic form using an ultrasonic vibrator is proposed by the present applicant (for example, paragraphs [0035] to [0040] and FIG. 7 of Japanese Patent Publication No. HEI07-163162).
Additionally, it is proposed by utilizing the above described characteristics that an ultrasonic motor is used as a driving source for moving a lens frame of a camera backward and forward by providing a vibrator integrally with the lens frame, which is a lens holding member, and by moving the lens frame backward and forward with reference to a fixed shaft with the vibrator (for example, see Abstract of the Disclosure, and FIG. 1 of Japanese Patent Publication No. HEI08-179184).
Also a card carrying apparatus using an ultrasonic motor is proposed. This ultrasonic motor comprises a ring-shaped vibration board that vibrates in multiple modes, and a pair of guide rails where grooves for guiding the vibration board are formed. As one of the guide rails, a movable rail is arranged, and presses the vibration board. As a result, the vibration board linearly moves along the guide rails by being vibrated (for example, see line 20 in the left column on page 3 to line 13 in the left column on page 4, and FIGS. 1 and 3 of Japanese Patent Publication No. HEI04-069072).
Furthermore, a linear ultrasonic motor that linearly moves a shaft by pressing a vibrator and the shaft to be driven with the use of a pressure roller, and by ultrasonic-vibrating the vibrator is proposed. Besides, it is recited that the cross section of the vibrator is made V-shaped or arc-shaped in the pressing part of the vibrator and the shaft (for example, see “Abstract of the Disclosure, and FIG. 1 of Japanese Patent Publication No. HEI09-149664).